Detection of GNSS Horizontal Position Using 3D - Track Map. Ing. Marek Jonas

Transcription

1 Detection of GNSS Horizontal Position Using 3D - Track Map Ing. Marek Jonas Department of Electrical Engineering

2 OUTLINE Differencies between railway and aviation safety concepts Problems of integrity of GNSS-based position for safety-related applications on railways Proposed method for detection of horizontal position error based on altitude Test of this method by simulation Summary of error behaviour of investigated satellite Department of Electrical Engineering 1

3 TRANSPORTATION SAFETY CONCEPTS Differencies ddd between safety concepts Railways Big difference Aviation CENELEC standards (EN 50126, EN 50129, EN a EN 50159) railway RAMS - reliability, availability, maintainability and safety Safety Integrity Levels (SIL) Aviation Target Level of Safety (TLS) concept defined by the International Civil Aviation Organization (ICAO) based on results from the statistical data of airplane accidents Department of Electrical Engineering 2

4 MOTIVATION Upcoming GALILEO SBAS are available (EGNOS,WAAS, MSAS, GAGAN, SNAS) Were designed according The aviation requirements For future use of satellite navigation systems on railways, increase of integrity of position solution is needed. The biggest task is satisfied of SIL 4 Torelable Hazard Rate THR = 10-9 /h Department of Electrical Engineering 3

5 PROPOSED METHOD New method for improvement of integrity of the position solution is proposed Simulation methodology Horizontal position is cruical in ground transportation Vertical position can be used for integrity check Possibility of detection of GNSS errors in horizontal plane by means of GNSS measured altitude was investigated by simulations Department of Electrical Engineering 4

6 RESULTS Pseudorange of SVN 12; +20 m HPE = 8.8 m Difference between actual and mean value of altitude = 12.7 m HPE exceeds HPL, hazardous misleading information (HMI), it can be detected by altitude Department of Electrical Engineering 5

7 SIMULATION RESULTS From the results implies that effects of errors in horizontal plane and vertical directions are nearly the same in this case Of the satellite with elevation of about 50 degrees. SHORTER PSEUDORANGE PR ERROR [M] HPE ALTITUDE DIFF LONGER PSEUDORANGE PR ERROR [M] HPE ALTITUDE DIFF PR ERROR is error in the pseudorange HPE is Horizontal Position Error ALTITUDE DIFF is difference between measured and real position Department of Electrical Engineering 6

8 SUMMARY OF ERROR BEHAVIOUR OF SVN 12 Behaviour of errors in horizontal plane is in the picture on the right An alarm limits can be set for altitude for detection of error in horizontal plane Department of Electrical Engineering 7

9 CONCLUSION Method for detection of the horizontal position error based on currrent value of altitude was described Method was tested by simulation The simulation implies that we can estimate the value of HPE according to current value of measured altitude in this case of satellite with elevation about 50 degrees According to results, this method is sensitive to errors caused by local effects which are not detectable by protection levels This method can help increase the integrity of GNSS-based positioning at the earth ground integrity is the key aspect of positioning from point of view of safety-related applications. Department of Electrical Engineering 8

10 ACKNOWLEDGEMENT & CONTACT Marek Jonas Department of Electrical Engineering Faculty of Electrical Engineering and Informatics University of Pardubice Czech Republic This research was supported by Internal Grant Agency of University of Pardubice SGS FEI 01/2013, by the grant GACR. Department of Electrical Engineering 9